1. Field of the Invention
This invention relates to automatic telephone answering apparatus that sends an OGM (Outgoing Message) recorded on a magnetic tape in advance to a calling party, records an ICM (Incoming Message) from the calling party on the magnetic tape, and can reproduce the recorded messages later.
2. Description of the Prior Art
Upon reception of an incoming call, a conventional automatic telephone answering apparatus sends an OGM, which is recorded on a first magnetic tape and indicates the start of automatic recording, to a calling party through a telephone line, and thereafter records an ICM from the calling party on a second magnetic tape. In apparatus of this type, in order to find the beginning or end of the OGM or ICM on the magnetic tape, position detection of the magnetic tape must be performed. In a conventional position detection system, the number of rotations of a reel table corresponding to a desired position of the magnetic tape is stored, and the number of rotations of the reel table during a given tape movement is detected by a counter. The detected value is compared with the stored value to detect the desired position of the magnetic tape. In another conventional system, a cue signal is recorded on the tape and is reproduced to detect the desired position of the magnetic tape.
However, in the former method, depending on the number of rotations of the reel table, high precision is required of a tape drive mechanism, a rotation detection mechanism, and brake characteristics of the reel table, and the like. In addition, the program of the microprocessor used in the control circuit is complicated. Therefore, this detection method inevitably increases apparatus cost.
In the latter system, using the cue signal, division signals for the respective ICMs and the end signal for all the ICMs are normally recorded without being distinguished from each other. Therefore, the division between ICMs cannot be distinguished from the end of all the ICMs during detection.
In another system, cue signals of different frequencies are recorded in the divisions between the respective ICMs and at the end of all the ICMs. In this case, a circuit for forming different frequency signals and a circuit for detecting them are necessary.
In addition, another system that can record a cue signal indicating the end of a most recently recorded ICM when the apparatus is set in the automatic answering mode is known. However, in this system, if a tape cassette is removed from the apparatus during the automatic answering mode, the end signal cannot be recorded on the tape.